You could (and often did) mod the rules prior to play, but the whole thing about wargaming is that, like board gaming, the rules are considered inviolate during an instance of play as a core assumption. In the origins of the game, Chainmail, there was no concept of straying from the rules – it was a wargame. Let’s stick mostly to the first two in the interest of space.

in the surrounding publications considered semi-canonical (Dragon magazine, nowadays forums and designer blogs), and.

implicitly in the text and detectable via textual analysis.

directly and explicitly in the rules text.The balance between Dungeon Master’s discretion versus reign of the rules versus player empowerment has always been debated in D&D circles but there’s a clear evolution of thinking across the span of versions. The allowed scope of DM rulings has absolutely changed over time in D&D. A recent question on RPG Stack Exchange had me researching the attitudes of Dungeons & Dragons towards rule interpretation over the years and I thought I’d expand it into a post here.

Hoyle's rules of dragon poker